Publications

Airborne monitoring of Mount St. Helens by the USGS began inMay 1980 for sulfur dioxide emissions and in July 1980 forcarbon dioxide emissions. A correlation spectrometer, orCOSPEC, was used to measure sulfur dioxide in Mount St.Helens' plume. The upward-looking COSPEC was mounted in afixed-wing aircraft and flown below and at right angles to theplume. Typically, three to six traverses...

No abstract available.

T he Earth is a bountiful source of heat. It continuously produces heat at depth, primarily by the decay of naturally radioactive chemical elements (principally uranium, thorium, and potassium) that occur in small amounts in all rocks. This deep heat then rises toward the cooler surface, where scientists can measure the rate of its escape through the Earth's crust. The annual heat loss...

No abstract available.

A 40‐km aperture trilateration network centered on the 1959 Hebgen Lake earthquake epicenter has been surveyed in 1973, 1974, 1976, 1978, 1981, 1984, and 1987. The deformation inferred from those surveys is described roughly by a uniaxial, 0.266 ± 0.014 μstrain/yr, N15°E ± 1°extension that is uniform in both time and space. That extension is orthogonal to the strike (N78°W ± 5°) of the...

Earthquakes struck the Klamath Falls area on Monday night, September 20, 1993, resulting in two deaths and extensive damage. The quakes were felt as far away as Coos Bay to the west, Eugene to the north, Lakeview to the east, and Chico, California, to the south. A foreshock recorded at 8:16 p.m. had a Richter magnitude of 3.9. The first of two main shocks, measuring 5.9 on the Richter...

Crater Lake caldera (8 × 10 km), formed 6845 years B. P. (14C age) during the climactic eruption of the volcanic edifice known as Mount Mazama, is intermediate in size between small calderas associated with central vent eruptions and large calderas that have ring fracture vent systems. Our quantitative study of lithic fragments in the ejecta confirms the existing model of changes in vent

Kilauea volcano, in Hawaii, may be the best understood basaltic volcano in the world. Magma rises from a depth of 80 km or more and resides temporarily in near-surface reservoirs: eruption begins when the crust above one of these reservoirs splits open in response to a pressure increase. Repeated rift-zone eruptions compress Kilauea's flanks; after decades of accumulation, the stress is...

No abstract available.

Type material of calcareous nannofossil index species Coccolithus crassus and two geographically widespread species Toweius magnicrassus and T. callosus have been studied by both light and SEM microscopy and morphometric measurements were made. Coccolithus crassus resembles Coccolithus pelagicus but has a raised cycle of elements around the centre of the distal shield. It probably...

About 6,000 specific‐gravity (SG) measurements of samples collected from nearly 200 granitic plutons comprising the central Sierra Nevada batholith yield a SG contour map across the batholith from 36.25° to 38° north latitude. With notable exceptions, SG decreases from values generally greater than 2.7 in the west to less than 2.6 over a few small areas of high‐silica, high‐potassium...

Volcanic eruptions are renowned for their violence and destructive power. This power comes ultimately from the heat and pressure of molten rock and its contained gases. Therefore we rarely consider the possibility that meteoric phenomena, like rainfall, could promote or inhibit their occurrence. Yet from time to time observers have suggested that weather may affect volcanic activity. In...